JS是运行在客户端的脚本（script）语言
引入JS进html
①sript标签内编写
<script type="text/javascript">document.write("<h1>hi</h1>")window.alert("who")
</script>②外部JS script src【CSS是link href】
<head><title>Document</title><link type="text/css" rel="2" href="URL.css"><script src="./ht.js"></script>
</head> ③内联
<body><button onclick="javascript:alert('hi')">anniu</button>
</body>var i=0;
var arr1=new Array(19);
var str=new String("hi");
var stu={
name:"me",
age:1
}
document.write("写入网页");
window.alert("弹出警告框" );
console.log("控制台输出");
String对象：属性length
Array对象：属性length 方法join() reverse() sort()
Date对象： myDate = new Date()
JS事件
| onClick | 点击 |
| onChange | 内容改变 |
| onFocus | 获得焦点 |
| onBlur | 失去焦点 |
| onLoad | 载入浏览器 |
| onUnload | 离开页面 |
| onMouseOver | 鼠标移到对象 |
| onMouseOut | 鼠标离开对象 |
| onMouseMove | 鼠标在对象上移动 |
| onMouseDown | 鼠标在对象上按下 |
| onMouseUp | 鼠标在对象上释放 |
| onSubmit | 提交表单 |
| onResize | 改变窗口大小 |
</head>
<script type="text/javascript">function hello(){alert("hi");}
</script>
<body><a href="./html2.html" onmousemove="hello()">link</a>
</body>windows.alert()警告框
windows.confirm()确认
windows.prompt()提示
document.write()
docunment.getElementById("").value
input类型：text password sumbit、reset、 checkbox(多选)、ratio（单选）
提交表单（<form action="提交到何处" method="get/post"）
</head>
<script type="text/javascript">function hello(){var name = document.getElementById("username").value;var password= document.getElementById("psw").value;alert(name+":"+password);}
</script>
<body><form action="">name <input type="text" id="username" ><br>psw <input type="password" id="psw"><input type="submit" id="sub" onclick="hello()"></form>
</body><textarea cols="" row=""></textarea> 文本域
下拉选框：
<select size="2" multiple="multiple"><option value="1">3</option><option value="2">4</option></select>
